Linear and rotary actuators are frequently equipped with optical sensors to monitor linear or rotational position and velocity of a moving element. The feedback signal provided by an optical sensor has a resolution that partly depends on the number of channels encoded on the surface monitored. The optical sensor head sees light reflected from areas on the moving surface, each series of light (or dark) areas comprising one channel in which the reflected light signals represent bits of data.
Prior art optical sensors have been developed in which light modulated by a pattern of reflecting or absorbing areas is conveyed through a sensor head via bundles of discrete micro-optical fibers. One such device includes 108 bundled fibers for each channel of data. The labor costs associated with producing an optical sensor system using this type of sensor head are relatively high due to the extensive tedious, skilled work required to assemble the bundles of micro-optical fibers required for splitting, routing, and combining transmit/receive channels. Depending on the resolution requirements of the system, typically from 3 to 12 data channels may be needed. Even if the number of separate optical fibers required for transmitting the modulated light is reduced by using, for example, time division multiplexing, the optical sensor may be quite expensive to manufacture.
It is, therefore, an object of this invention to reduce the costs associated with manufacturing an optical sensor. A further object, with respect to such an optical sensor, is to distribute light between channels by combining and/or splitting the light without using optical fiber junctions. Yet a further object is to produce an optical sensor incorporating an integral waveguide having a plurality of optical channels. These and other objects and advantages of the present invention will be apparent from the attached drawings and the description of the preferred embodiments that follows.